1. Technical Field
The present invention relates to a liquid ejecting apparatus including a liquid ejecting head for ejecting a liquid from nozzle openings and a method of driving a liquid ejecting head.
2. Related Art
An ink jet recording apparatus such as an ink jet printer or plotter includes an ink jet recording head for ejecting an ink stored in an ink storage unit such as an ink cartridge or an ink tank as ink droplets.
The ink jet recording head includes pressure generation chambers communicating with nozzle openings, a reservoir which is a common liquid chamber communicating with the plurality of pressure generation chambers, and pressure generation units for causing pressure variations in the pressure generation chambers and ejecting ink droplets from the nozzle openings. As the pressure generation units mounted in the ink jet recording head, for example, a longitudinal vibration piezoelectric element, a deflection piezoelectric element, a device using electrostatic force and a heating device may be used.
When the ink droplets are ejected by such an ink jet recording head, a problem that the tail portions of the ejected ink droplets are lengthened or secondary minute ink droplets is ejected may occur. If such a problem is caused, the high-frequency ejection for ejecting a plurality of ink droplets at an earlier timing cannot be performed and thus high-speed printing cannot be performed.
Accordingly, provision of an expansion element for expanding pressure generation chambers and cutting ink columns after a contraction element for contracting the volume of the pressure generation chambers and ejecting ink droplets as a driving signal supplied to pressure generation units such as piezoelectric devices is suggested (for example, see JP-A-2-184449, JP-A-2006-306076, and Japanese Patent No. 3275965).
However, since higher-speed printing is required, the tail portions of the ink droplets need to be further decreased. Accordingly, a voltage may be rapidly changed by increasing the driving voltage of the expansion element for cutting the ink columns and reducing a time for applying the voltage. However, if the voltage is rapidly changed, the vibration of the meniscus of the ink of the nozzle openings after the ink droplets are ejected is increased. Accordingly, a problem that secondary ink droplets are ejected or the ejection of the next ink droplets undergoes a bad influence occurs.
Such a problem cannot be solved by JP-A-2-184449, JP-A-2006-306076, and Japanese Patent No. 3275965. Such a problem remarkably occurs when an ink having high viscosity is ejected.
Such a problem occurs even in a liquid ejecting apparatus for ejecting a liquid excluding an ink as well as the ink jet recording apparatus.